FileSalvage is a data recovery utility specifically designed for the macOS operating system. Its primary function is to recover files that have been accidentally deleted, retrieve data from corrupted or erased volumes, and salvage information from failing hard drives. Given that Charles is using a Mac computer and needs to recover a deleted file, FileSalvage is the most appropriate tool among the choices as it is built to handle macOS file systems like HFS+ and APFS.

A. Xplico is a Network Forensic Analysis Tool (NFAT) used to extract data from captured internet traffic (e.g., pcap files), not for recovering files from a local disk.

B. Colasoft’s Capsa is a network protocol analyzer (packet sniffer) designed for network monitoring, analysis, and troubleshooting, not for local file system data recovery.

D. DriveSpy is a DOS-based forensic tool used for low-level disk viewing and data acquisition. It is not designed for modern macOS file systems.

1. FileSalvage: SubRosaSoft, the developer of FileSalvage, describes the tool's capabilities for macOS. The official product page states, "FileSalvage is an extremely powerful Macintosh application for exploring and recovering deleted files from a drive or drive image." (Source: SubRosaSoft Official Documentation). While a direct link to vendor documentation is provided for context, the classification of the tool is standard in the digital forensics domain.

2. Xplico: The official Xplico documentation describes its purpose: "The goal of Xplico is to extract from an internet traffic capture the applications data contained." This confirms its role as a network forensics tool, not a disk recovery tool. (Source: Xplico Official Documentation, 'About' section).

3. Colasoft’s Capsa: The official vendor documentation for Capsa states it is a "portable network analyzer for both LANs and WLANs which performs real-time packet capturing capability...". This clearly defines it as a network analysis tool. (Source: Colasoft Official Website, Capsa Product Description).

4. DriveSpy: In academic literature, DriveSpy is categorized as a command-line forensic tool for DOS. For instance, "DriveSpy from Digital Intelligence is a forensics tool for viewing and acquiring sectors from a disk." This tool is not intended for use on modern macOS. (Source: Nelson, B., Phillips, A., & Steuart, C. (2015). Guide to Computer Forensics and Investigations. Cengage Learning. Chapter 7, "Current Computer Forensics Tools," section on "Other Forensics and Data-Recovery Tools").